Fire Weather Watchers
Peter Felsch hangs up the phone. "They're getting half-inch hail in Deer Lodge," he says.
Jean checks a topo map to determine the slope and exposure for the area of the fire forecast she's making.

Jean Hoadley joins him in front of a large monitor displaying a garishly-colored Doppler radar map of western Montana. Together they watch the thunderstorm head north in time-lapse. Little yellow daggers mark lightning strikes across the storm's track. Peter sends an alert over the wire, ending with the sober advice:

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS.

This is all routine at the National Weather Service office in Missoula, where forecasters like Jean and Peter eavesdrop on every movement of the atmosphere in the hope of predicting what it will do next, in an effort to help communities, businesses and wildland firefighters.

Flame-fighting Forecasts

Fire is fundamentally a meteorological event. Not only does lightning start 15,000 fires a year across the county, but two components of fire -- heat and air -- are dictated by the weather. So when fire managers try to decide how or even whether to fight a blaze, the first thing they do is request a "spot forecast" from the weather service.

So when lightning ignites a fire in Montana's Selway Bitterroot Wilderness Area, Jean quickly reviews basic information supplied by the fire crew to build her spot forecast. She locates the fire on a topographical map to see how the terrain will interact with larger air movements. "It can be real hard here in the mountains," she says. "The fronts tend to get all broken up and the winds do all kinds of crazy things. It's not like the Midwest, but we can try."

First she checks the relative humidity from readings in the field, then she consults a computer screen filled with outlines of blobs-within-blobs. It's like a topographic map of the air, but instead of marking land elevations, the lines represent air pressure at a given altitude. Where there's a large pressure difference, air masses will move "downhill" on the maps -- a movement felt on the ground as wind. For firefighters, wind can mean bigger fires and potentially dangerous conditions.

Along with wind, moving air brings temperature and humidity changes. Jean eyeballs a satellite image depicting water vapor is in the atmosphere. The animation shows wet and dry air eddying in huge streams. This fire crew is in luck -- a pocket of cooler, damper air will arrive in their neck of the woods tomorrow. These conditions can be the make-or-break factor in easily containing a fire.

Without natural humidity and lower temperatures to cool off the fuel, firefighters have to substitute dirt, water and retardant. Their job is much easier when they can rely on nature.

High-tech sensors and complex computer models have largely replaced traditional tools.

An Eye on the Sky

Jean sends her forecast to the fire dispatcher for radio relay to the crew at the scene. Her report carefully blends the computer predictions with real-world observations and is then adjusted for the altitude and terrain at the fire site. "You always have to take into account what's really going on out there versus what the model is saying," she says.

To that end, Peter heads out the door to look at the sky before he files his next scheduled report. "These windows aren't big enough," he says over his shoulder.